The present invention relates to a method of data acquisition and processing of mass spectral data and a mass spectrometer.
In existing state of the art mass spectrometers an additional short time interval is allocated between spectral acquisition periods during which time interval no data is acquired or stored. During this time interval the state or mode of the system may be changed and the system allowed to equilibrate. This equilibration can consist of allowing power supplies to settle and allowing populations of ions within the mass spectrometer to exit etc.
Changing of the mode of operation is generally synchronized to the start of the inter scan period or time interval. This approach ensures that ions associated with the first mode of operation do not appear in a mass spectrum relating to the second mode of operation. This mixing of ion populations is often referred to as crosstalk. However, synchronization involves complex instrument control and, to ensure no crosstalk between modes, the inter scan period or time interval may be longer than that required to simply change the system parameters from one mode to another. This reduces the duty cycle for the acquisition of data.
U.S. Pat. No. 6,111,250 discloses a method of reducing the pause time required to allow a collision gas cell to drain of ions between introductions of precursor ions with differing mass to charge ratio values. The synchronized pause time is present to ensure minimum crosstalk.
Examples of acquisitions where the mode or state of the mass spectrometer is changed during an acquisition include: switching between different precursor ions during an MS-MS experiment, switching between different CID collision energies and switching from positive to negative ion operation, etc.
It is desired to provide an improved method of data acquisition, an improved method of mass spectrometry and an improved mass spectrometer.